Conventionally, as shown in a cross-sectional perspective view in FIG. 1, a core ring 110 of a turbine or impeller of a torque converter includes a rounded outer diameter 112 that is part of a curved blade side surface 114 of the core ring 110. At outer diameter 112, blade side surface 114 joins with an outer diameter of a radially extending edge 116, which extends perpendicular to a center axis of core ring 110. At an inner diameter thereof, blade side surface 114 joins an inner diameter edge 120, which extends axially and radially outward from the inner diameter of blade side surface 112 to join an inner diameter of a curved stator side surface 122 of core ring 110. Stator side surface 122 extends radially outward, while extending axially to a lesser degree, from curved stator side surface 122 to an inner diameter of radially extending edge 116. Core ring 110 has a constant thickness and both blade side surface 112 and stator side surface 122 follow the same curved path while extending radially outward and axially from edge 120 to edge 116. Slots 124 for receiving connecting tabs of turbine or impeller blades are formed in an interior of core ring 110, i.e., between edges 116, 120, and through core ring 110 from stator side surface 122 to blade side surface 112.
It is also known to provide undercuts 126 in radially extending edge 116, as shown in FIG. 2, extending from surface 114 to surface 122. Undercuts 126 are only for manufacturing purposes and do not have any influence on the performance of the core ring. Undercuts 126, on both sides of the carrying tab, keep the part attached to strip and providing a stretch web to let the material flow during forming. The part is pierced out in the last station of the progressive die only by cutting the carrying tabs on the outer diameter. Undercuts 126 can cause week points (stress risers) if high pressure is applied. These are the areas were failure can occur.